In the vapor deposition technology of AMOLED (Active-matrix organic light emitting diode), the vapor deposition material has a uniform film thickness in the pixel region, and IJP-AMOLED (inkjet printing AMOLED) uses hydrophilic liquid ink to form a film. The residue of the hydrophobic PDL (Pixel Define Layer) material in the Bank region (pixel region) directly affects the spreading of the ink, resulting in abnormal pixel function and ultimately affecting the display effect. For example, as shown in FIG. 1, 1′ is a TFT (Thin Film Transistor) backplane, 2′ is a planarization layer, 3′ is a pixel defining layer, and 4′ is an anode. As shown in FIG. 2, 30′ is a pixel defining layer after being patterned and having a notch 31′ formed thereon, the anode 4′ is exposed through the notch 31′, and a pixel defining layer material 32′ is remained on the anode 4′. As shown in FIG. 3, when the ink layer 5′ is formed on the anode 4′ by inkjet water (the ink material may be a material for illuminating), there is a blank region 41′ around the remaining pixel defining layer material 32′ without covering by the ink layer 5′, which affects the display effect of the AMOLED.
Therefore, good ink spread ability greatly determines the product quality of the IJP-AMOLED, so it is especially important to clean the Bank region before printing ink. The PDL material is an organic photosensitive material, and the Bank region is formed by a yellow light and an OVEN process (baking process), and the PDL material residue in the pixel region after the PDL layer is developed directly affects the ink spread ability. Currently, the PDL material residue for vapor deposition of the AMOLED pixel region is often subjected to a dry etching process after the PDL yellow light process. However, the use of the dry etching process after the PDL yellow light process of IJP-AMOLED brings the following problems:
1. The dry etching destroys the surface structure of PDL, which makes the PDL lose its hydrophobicity. Therefore, the ink dropped in the IJP process tends to adhere to the surface of the Bank region instead of flowing into the Bank region.
2. The dry etching causes a certain degree of loss of the thickness and line width of the PDL, affecting the confirmation of the ink drop amount and the aperture ratio of the pixel.